(1) Field of the Invention
The invention relates to a wheel suspension for a vehicle, in particular for a vehicle such as a trailer with a driving axle for the transport of heavy loads, comprising an axle-bearing arm extending towards the front or the rear of the vehicle, this arm, on the one hand, being mounted in a pivoting way, at its one end, onto a cover plate inserted against a bearing structure for the axle-driving organ and, on the other hand, cooperating, in particular through its opposite end, with shock-absorbing means interposed between this arm and said bearing structure.
The present invention relates, in particular, to the field of the transport vehicles such as trailers with a driving axle.
(2) Description of the Related Art
In this respect, one should note that in the harbor or airport areas, there can very often be seen vehicles with a set of trailers, the latter being mounted on driving axles and connected to each other by hinging means forming control means for the orientation of these driving axles, with a view to a bicycle-gear-type movements of the set.
Presently, the wheels of such trailers are seldom sprung, which is a problem for the transport of heavy loads, since the passing of obstacles at the level of the -road results into huge stresses at the level of both the trailer and the load itself. Now one can observe that the grounds on which this kind of set of trailers with a bicycle-gear-type of movement has to move are increasingly more uneven. whereas the size of the trailers and the weight of the transported loads, have a tendency to increase.
In this context, one has already thought of using blade springs for springing the wheels of such trailers, which has some drawbacks.
First of all, these blade springs are of a not inconsiderable size and require the loading platform of these trailers to be raised.
In addition, their range of spring movement is relatively large and results in a coupling-pole height varying according to whether the trailer is loaded or not. Under such circumstances, it is particularly difficult to contemplate the possibility of automatically coupling or uncoupling the trailers to or from each other. Now, it should, as a matter of fact, be possible to perform these operations without it being necessary for the driver to leave his towing vehicle. As a matter of fact, one should note that, in order to allow such an automatic uncoupling and, inversely, coupling of these trailers, the latter are provided, at the level of their front axle, with a coupling pole on which acts a system for self-compensating the load that allows it to be automatically maintained horizontal. Furthermore, the fastening the rear driving axle receives is provided with a round groove facilitating the insertion, at the level of this fastening, of the free end of the coupling bar of the next trailer.
Besides that, there are also known wheel-suspension systems that consist of an axle-bearing arm substantially extending towards the front or, as the case may be, towards the rear of the vehicle and one end of which is mounted in a pivoting way on a cover plate made integral with the chassis of said vehicle. Between this arm, which the axle receiving the wheels at its ends is hence fixed to, and said chassis of the vehicle are also interposed shock-absorbing means in the form of a spring directly made integral, at its ends, with this arm and with the chassis. Such shock-absorbing means can also be in the form of a cylindrical block or a pneumatic or oil and air system.
In this respect, though the solution of the cylindrical block is not suitable for the transport of heavy loads, whereas a pneumatic system requires the installation on the vehicle of a large reserve of air, because of the large difference between the weight when unloaded and the total weight when loaded, a spring of a helical type the ends of which are fixed to the axle-bearing arm and at the level of the vehicle must act not only in compression, but also in bending. This not only causes the mechanical parts of the wheel suspension to operate in bad conditions, but, in the case of a driving axle, such a wheel suspension can have an influence on the orientation of this axle, which impedes the correct working of the bicycle-gear-type movement of a set of trailers.
To this end, the invention relates to a wheel suspension for a vehicle, in particular for a vehicle such as a trailer with a driving axle for the transport of heavy loads, comprising an axle-bearing arm extending towards the front or the rear of the vehicle, this arm, on the one hand, being mounted in a pivoting way, at its one end, onto a cover plate inserted against a bearing structure for the axle-driving organ and, on the other hand, cooperating, in particular through its opposite end, with shock-absorbing means interposed between this arm and said bearing structure and consisting of a helical spring so designed as to be capable of acting exclusively in compression under the action of means that ensure its hold and guiding and that are in the form of two parts fitting into each other while being capable of sliding in each other in the direction axial to the spring, against the action of the latter, these parts being mounted in a pivoting way about a spindle parallel to the axle, one of them on said axle-bearing arm and the other one on said bearing structure, and, on the other hand, an axle is fixed on a bearing arm so as to be substantially located on the vertical axis of pivoting of the driving organ of this axle.
According to another feature of the present invention, the axle-bearing arm includes means for receiving and fixing the axle, taking into consideration, in this respect, that these fixing means can be inserted at a determined distance from the pivoting end of said bearing arm, according to the amplitude of the range of spring movement such a wheel suspension should allow.
The advantages resulting from the present invention reside in that in order to cope with the problem set forth, it is enough to use a helical spring and not a pneumatic system, which is necessarily more voluminous, while this spring is impeded from acting in any other way than in compression, which, otherwise, would result into putting the elements of the wheel suspension under stress, even result in having an influence on the orientation of the wheels, wherein such difficulties could not have been eliminated in another way than by using very complex and, of course, expensive mechanical retaining means for the bearing arm.